Contradiction with Matthew 5:39
While 1 Kings 20:9 depicts a refusal and assertive stance, Matthew 5:39 teaches to not resist evil and to turn the other cheek.
Matthew 5:39: But I say unto you, That ye resist not evil: but whosoever shall smite thee on thy right cheek, turn to him the other also.
Contradiction with Romans 12:18
1 Kings 20:9 shows a decision to set boundaries with an enemy, whereas Romans 12:18 advises living peaceably with all men as much as possible.
Romans 12:18: If it be possible, as much as lieth in you, live peaceably with all men.
Contradiction with Proverbs 25:21
Proverbs 25:21 suggests feeding your enemy if they are hungry, which contrasts with the negotiation refusal in 1 Kings 20:9.
Proverbs 25:21: If thine enemy be hungry, give him bread to eat; and if he be thirsty, give him water to drink: